GUI: add tooltips
|Reported by:||criezy||Owned by:||sev-|
Some of the options in the ScummVM Launcher are a bit criptic or not obvious. For those it might help to have tooltips (with an option to turn tooltips off if we don't want them).
There are alternatives such as using inline help (but the GUI is already crowded) or a separate documentation (the the user will usually not read unless he has a blocking problem, and he will therefore miss some features).
Ticket imported from: #2821513. Ticket imported from: feature-requests/533.